To add the prefix " guided " to the phrase " Lamb wave " is thus to recognize that Lamb's infinite plate is, in reality, nowhere to be found.
12.
Substantial improvements in the accuracy of AE source location ( a major techniques of AE testing ) can be achieved through good understanding and skillful utilization of the Lamb wave body of knowledge.
13.
For particles on the plate surface, these conditions occur when the Lamb wave phase velocity is " " 2c t " or " c l ", respectively.
14.
A major challenge and skill in the use of Lamb waves for ultrasonic testing is the generation of specific modes at specific frequencies that will propagate well and give clean return " echoes ".
15.
But even in ultrasonic testing, mode conversion takes place when the generated Lamb wave interacts with flaws, so the interpretation of reflected signals compounded from multiple modes becomes a means of flaw characterization.
16.
For example, in a ?inch ( 19mm ) thick steel plate at a frequency of 200 kHz, the first four Lamb wave modes are present and at 300 kHz, the first six.
17.
Here " c " can be either the longitudinal wave velocity or the shear wave velocity, and for each resulting set of resonances the corresponding Lamb wave modes are alternately symmetrical and antisymmetric.
18.
This phrase is quite often encountered in non-destructive testing . " Guided Lamb Waves " can be defined as Lamb-like waves that are guided by the finite dimensions of real test objects.
19.
EMAT is an ideal transducer to generate Shear Horizontal ( SH ) bulk wave mode, Surface Wave, Lamb waves and all sorts of other guided-wave modes in metallic and / or ferromagnetic materials.
20.
These computational tools, along with a more widespread understanding of the nature of Lamb waves, made it possible to devise techniques for nondestructive testing using wavelengths that are comparable with or greater than the thickness of the plate.
